NAME
Vi::QuickFix - Support for vim's QuickFix mode
SYNOPSIS
use Vi::QuickFix;
use Vi::QuickFix ;
use Vi::QuickFix ;
use Vi::QuickFix ;
where "" is one or more of "silent", "sig", and "tie".
DESCRIPTION
When "Vi::QuickFix" is active, Perl logs errors and warnings to an
*error file* named, by default, "errors.err". This file is picked up
when you type ":cf" in a running vim editor. Vim will jump to the
location of the first error recorded in the error file. ":cn" takes you
to the next error, switching files if necessary. There are more QuickFix
commands in vim. Type ":help quickfix" for a description.
To activate QuickFix support for a Perl source, add
use Vi::QuickFix;
or, specifying an error file
use Vi::QuickFix '/my/errorfile';
early in the main program, before other "use" statements.
To leave the program file unaltered, Vi::QuickFix can be invoked from
the command line as
perl -MVi::QuickFix program
or
perl -MVi::QuickFix=/my/errorfile program
"Vi::QuickFix" is meant to be used as a development tool, not to remain
in a distributed product. When the program ends, a warning is issued,
indicating that "Vi::QuickFix" was active. This has the side effect that
there is always an entry in the error file which points to the source
file where "Vi::QuickFix" was invoked, normally the main program. ":cf"
will take you there when other error entries don't point it elsewhere.
Use the "silent" option with "Vi::QuickFix" to suppress this warning.
It is a fatal error when the error file cannot be opened. If the error
file is empty (can only happen with "silent"), it is removed at the end
of the run.
ENVIRONMENT
"Vi::QuickFix" recognizes the environment variable
"VI_QUICKFIX_SOURCEFILE"
When Perl reads its source from "STDIN", error messages and warnings
will contain the string "-" where the source file name would otherwise
appear. The environment variable "VI_QUICKFIX_SOURCEFILE" can be set to
a filename, which will replace "-" in those messages. If no "-" appears
as a file name, setting the variable has no effect.
This somewhat peculiar behavior can be useful if you call perl (with
"Vi::QuickFix") from within a vim run, as in ":w !perl -MVi::QickFix".
When you set the environment variable "VI_QUICKFIX_SOURCEFILE" to the
name of the file you are editing, this fools vim into doing the right
thing when it encounters the modified messages.
This is an experimental feature, the behavior may change in future
releases.
USAGE
The module file .../Vi/QuickFix.pm can also be called as an executable.
In that mode, it behaves basically like the "cat" command, but also
monitors the stream and logs Perl warnings and error messages to the
error file. The error file can be set through the switches "-f" or "-q".
No warning about QuickFix activity is issued in this mode.
Called with -v, it prints the version and exits.
IMPLEMENTATION
For a debugging tool, an implementation note is in order.
Perl offers to obvious ways to watch and capture its error output. One
is through the (pseudo-) signal handlers $SIG{__WARN__} and
$SIG{__DIE__}. The other is through "tie"-ing the "STDERR" file handle.
"Vi::QuickFix" can use either method to create the error file. As it
turns out, the ability to tie "STDERR" is relatively new with Perl, as
of version 5.8.1. With Versions 5.8.0 and earlier, a number of internal
errors and warnings don't respect tie, so this method cannot be used.
With Perl versions ealier than 5.8.1, "Vi::QuickFix" uses %SIG handlers
to catch messages. With newer versions, "Vi::Quickfix" ties "STDERR" so
that it (additionally) writes to the error file.
A specific method can be requested through the options "sig" and "tie",
as in
use Vi::QuickFix qw( sig);
Requesting "tie" with a Perl version that can't handle it is a fatal
error, so the only option that does anything useful is "sig" with a
new-ish Perl. It can be useful when "tie"-ing "STDERR" conflicts with
the surrounding code.
CONFLICTS
Such a conflict can occur with the "sig" method as well, and it can
happen in two ways. Either "Vi::QuickFix" already finds a resource (a
%SIG handler or a tie on "STDERR") occupied at "use" time, or the
surrounding code commandeers the resource after the fact.
All such conflicts can be avoided by using "Vi::QuickFix" in a separate
process, as noted under ""USAGE".
However, if "STDERR" is already tied when "Vi::QuickFix" is "use"d, it
cannot employ the "tie" method, and by default reverts to "sig". If the
"tie" method is specifically requested, a fatal error results.
If the "sig" method finds one of the handlers ("__WARN__" and "__DIE__")
already occupied, it chains to the previous handler after doing its
thing, so that is not considered an obstacle. "Chaining" file ties is
harder, and has not been attempted.
If "Vi::QuickFix" is already active, the surrounding code may later
occupy a resource it is using. There is little that can be done when
that happens, except issue a warning which is also logged to the error
file. This can help in finding the source of the conflict. In "silent"
mode, no such warning is given.
The warning is triggered when the corresponding resource is overwritten,
except when the overwriting program keeps a copy of it. It is then
assumed that the program will keep it functioning. Since we're still
talking implementation -- it is actually triggered through a DESTROY
method when the corresponding object goes out of scope. %SIG handlers
are code objects just for this reason.
VERSION
This document pertains to "Vi::Quickfix" version 1.129
BUGS
"no Vi::QuickFix" has no effect
AUTHOR
Anno Siegel
CPAN ID: ANNO
siegel@zrz.tu-berlin.de
http://www.tu-berlin.de/~siegel
COPYRIGHT
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
The full text of the license can be found in the LICENSE file included
with this module.
SEE ALSO
perl(1), vim(1).